Field
The present application relates generally to network equipment typically used in data centers, and more particularly to network devices with increased port density and efficiency.
Description of the Related Art
Traditionally, data center network devices, such as servers, storage devices, switches, and routers, as well as NIC cards that may be added to such devices have physical connection points to transmit and receive data. These connection points generally include a transceiver and a connector, which are often referred to as a port. Ports can be copper or fiber ports that are built into the device, or the ports can be plug-in modules that contain the transceiver and connector and that plug into Small Form Factor (SFF) cages intended to accept the plug-in transceiver/connector module, such as SFP, SFP+, QSFP, CFP, CXP, and other transceiver/connector modules, where the connector extends from an exterior surface of the device, e.g., from a front panel. Fiber ports may be low density or single fiber ports, such as FC, SC, ST, LC, or the fiber ports may be higher density MPO, MXC, or other high density fiber ports.
Fiber optic cabling with the low density FC, SC, ST, or LC connectors or with SFP, SFP+, QSFP, CFP, CXP or other modules either connect directly to the data center network devices, or they pass through interconnector cross connect patch panels before getting to the data center network devices. The cross connect patch panels have equivalent low density FC, SC, ST, or LC connectors, and may aggregate individual fiber strands into high density MPO, MXC or other connectors that are primarily intended to reduce the quantity of smaller cables run to alternate panels or locations.
FIG. 1 shows a prior data center network device 10, that is a network switch, with ports 110, each having a transceiver 111 and connector 112, mounted internally to the device 10, such that the connector extends out of a front or rear panel of the device. CPU 102 configures switch logic 104 to direct internal data streams (not shown) out via paths 108 through transceiver 111 and connector 112 in port 110. Ports 110 may be copper or fiber ports. Typically, a copper cable (cable 114A) is terminated with an RJ-45 connector (connector 116A), while fiber cable (cable 114B) is terminated with an FC, SC, ST, or LC connector (cable 116B).
FIG. 2 shows a prior data center network device 20 where SFF cages 118 and 124 are mounted within the device 20, typically to a front or rear panel, and external transceiver/connector modules can be inserted into SFF cages 118 or 124. CPU 102 configures switch logic 104 to direct internal data streams (not shown) out via paths 108 through transceiver 121 and connector 122, or through transceiver 126 and connector 128. In this configuration, connectors 122 can consist of either single copper RJ-45 connectors, or single or duplex fiber connectors. Duplex fibers in this case are for bidirectional path communications. Connectors 128 can consist of multi-fiber connectors, such as MPO multifiber connectors.
Using SFP or SFP+ transceiver modules permits a single connection to be configured between two data center network devices at data rates of up to 10 Gbps. Using QSFP, CFP, CXP, or other transceivers permits a single connection to be configured between two data center network devices at data rates of up to and beyond 100 Gbps.
MPO multifiber connectors are used for IEEE 802.3ba industry standard 40 Gbps and 100 Gbps bandwidth fiber connections. FIG. 3 shows IEEE 802.3ba 40GBASE-SR4 optical lane assignments where 40 Gbps bandwidth is achieved by running four fibers of 10 Gbps in one direction (Tx) for the 40 Gbps transmit path, and four fibers of 10 Gbps in the other direction (Rx) for the 40 Gbps receive path. This means four fibers in the 12 fiber MPO are unused, thus decreasing connector and cable efficiency.
100 Gbps bandwidth fiber connections are achieved by running 10 fibers of 10 Gbps in one direction (Tx) for the 100 Gbps transmit path, and 10 fibers of 10 Gbps in the other direction (Rx) for the 100 Gbps receive path. FIG. 4A shows two IEEE 802.3ba 100GBASE-SR10 optical lane assignments for 12 fiber MPO's, where one MPO uses 10 fibers of 10 Gbps for the 100 Gbps transmit path (Tx), leaving 2 fibers unused, and the other MPO uses 10 fibers of 10 Gbps for the 100 Gbps receive path (Rx), leaving 2 fibers unused, again decreasing connector and cable efficiency. FIG. 4B shows a 24 fiber MPO, where 10 fibers of 10 Gbps are used for the 100 Gbps transmit path (Tx), plus 10 fibers of 10 Gbps are used for the 100 Gbps receive path (Rx), leaving a total of 4 unused fibers, again decreasing connector and cable efficiency.
There also exists a standard for 100 Gbps transmission which uses four 25 Gbps fiber data rate connections configured similar to the 40 Gbps standard, where eight fibers (four transmit and four receive fibers) are used in a 12 fiber MPO. Implementing this standard means that four fibers in a 12 fiber MPO are not used, again decreasing connector and cable efficiency.
In each of these cases, the industry standard method of migrating from a 10 Gbps connection to a 40 Gbps or 100 Gbps connection, or from a 40 Gbps connection to a 100 Gbps connection requires reconfiguring the fiber transmit and receive paths by physically changing the ports within the data center network devices increasing the cost to run the data center. Adding further to the cost to run the data center is that this change has to occur at both ends of the path (i.e., the receive port and the transmit port) as well as the cabling there between.
In many cases, the entire data center network device has to be upgraded as the transceiver/connector configuration of FIG. 1, or the transceiver/connector/SFF cage configuration of FIG. 2 cannot support the higher data rate speeds on the additional fiber ports associated with 40 Gbps or 100 Gbps ports. Further, in each of the configurations described above, fibers are left unused in the connectors and cables, thus wasting resources and unnecessarily increasing costs for the higher fiber cabling and connectors. To illustrate, connector 132 (seen in FIG. 2) is a 12 fiber MPO connector and fiber cable 130 is a 12 fiber cable. To use this cable and connector in a 40 Gbps or 100 Gbps application would leave 2 or 4 fibers unused, depending upon the type of port used.
Further, in current network devices the ports 110 (i.e., the transceiver 111 and connector 112 in FIG. 1, or the transceiver 121, connector 122 and SFF cage 118 in FIG. 2) are connected directly to front or rear panels of the network device. The physical size of the transceiver or SFF module significantly limits the number of connectors 112 or cages 118 that can be installed on the front or rear panels of the network device, thus limiting the ability to cost effectively increase port density.